A high-pressure pump provided in a fuel supply system has been known. The high-pressure pump pressurizes fuel in the system to supply the pressurized fuel to an internal combustion engine.
The high-pressure pump pressurizes the fuel by varying a volume of a pressure chamber formed in a deep portion of a cylinder in accordance with reciprocating movement of a plunger provided inside the cylinder. The fuel pressurized by the pressure chamber is discharged from a discharge path communicating with the pressure chamber.
According to an example of a high-pressure pump described in Patent Literature 1, a ring-shaped member fits to a radially outer portion of a plunger on the side exposed to a pressure chamber. This high-pressure pump prevents separation of the plunger from a cylinder by engagement between the ring-shaped member and a step portion formed between the pressure chamber and the cylinder in a state before attachment to an internal combustion engine.
According to another example of the high-pressure pump described in Patent Literature 1, the outside diameter of the plunger at a portion protruding from the cylinder toward the side opposite to the pressure chamber is smaller than the outside diameter of the plunger at a portion inside the cylinder. The plunger therefore has a step at the portion corresponding to the change of the outside diameter of the plunger. This high-pressure pump similarly prevents separation of the plunger from the cylinder by engagement between the step of the plunger and a step portion of a pump body in a state before attachment to an internal combustion engine.
According to the high-pressure pump described in Patent Literature 1, a suction valve unit that controls supply of fuel to the pressure chamber is provided on the pressure chamber on the side opposite to the plunger. The suction valve unit is detachably attached to the pump body. This configuration of the high-pressure pump allows insertion of the plunger from the pressure chamber into the cylinder before assembly of the suction unit to the pump body.
According to the high-pressure pump described in Patent Literature 1, however, the size of the high-pressure pump in the axial direction of the cylinder increases by the presence of the suction valve unit described above. When the position of the suction valve unit of the high-pressure pump described in Patent Literature 1 is switched to a position in the radial direction of the cylinder, and the pressure chamber on the side opposite to the plunger is closed by the pump body, for example, assembly of the plunger to the cylinder from an opening of the cylinder on the side opposite to the pressure chamber is difficult in any of the examples described above.